Lamp fittings for tungsteniodine lamps



June 25, 1968 R. c; KEMBER ETAL 3,390,372

LAMP FITTINGS FOR TUNGSTEN-IODINE LAMPS Filed July 7, 1954 ALFRED JOHN BURNETT RONALD WILLIAM GOSLlNG RAYMOND CHARLES KEMBER lA/VE N TOIZS United States Patent 0 3,390,372 LAMP FITTINGS FOR TUNGSTEN- IODINE LAMPS Raymond Charles Kember, Alfred John Burnett, and Ronald William Gosling, London, England, assignors to Thorn Electrical Industries Limited, London, England, a British company Filed July 7, 1964, Ser. No. 380,801 Claims priority, application Great Britain, July 11, 1963, 27,580/ 63 7 Claims. (Cl. 339-112) The present invention relates to lamp fittings including means for cooling part of the envelope of the lamp mounted in the fitting.

The invention is concerned particularly with fittings for use with tungsten-iodine lamps, though fittings in accordance with the invention can also be used with other types of lamps. A tungsten-iodine lamp has to be operated at a high wall temperature, typically about 800 C. in order to achieve high efliciency. For this reason the lamp envelope is preferably made of fused quartz or similar material having a high silica content. The lead-in conductors for supplying current to the lamp filament are conveniently wires or strips of molybdenum which will form a satisfactory seal with the material of the lamp envelope. In order to prevent deterioration of the lead-in conductors and the seal which they form with the envelope it is desirable to maintain them at a lower temperature than that of the main part of the envelope and it is an object of the present invention to provide a fitting which incorporates means for cooling the molybdenum seal of such a lamp to maintain it at a temperature substantially below the operating temperature of the lamp envelope.

In accordance with the invention there is provided a lamp fitting including a heat-conducting metal housing, a contact member mounted within the housing for engagement with a contact of the lamp, and a metal clip mounted on the housing and having jaws adapted to engage a part of the lamp envelope to be cooled, the clip being adapted to conduct heat from the said part to the housing.

One known type of tungsten-iodine lamp has a coiled filament supported along the axis of a tubular envelope. The ends of the filament are attached to strips of molybdenum which pass through seals at the ends of the lamp envelope. The molybdenum strips are embedded in the fused quartz of the envelope by pressing and flattening the walls of the envelope against the sides of the strips to form these seals. Ceramic end pieces are mounted on the outer ends of the seals and carry button contacts to which the molybdenum strips are connected. By way of example the invention will be described as embodied in a fitting for such a lamp, parts of which are shown in the accompanying drawings, in which:

FIG. 1 is a section of one end of the fitting showing a lamp holder supporting one end of the lamp, and

FIG. 2 is an end view of part of the holder, seen from the right in FIG. 1.

FIG. 1 shows one end of the lamp which has a tungsten filament 3 supported within an envelope 4 by supports 5, and connected by a molybdenum strip 6 embedded in a seal 7 to a button contact carried by a ceramic end piece 8. This contact engages in a socket contact 11 supported in the end of a ceramic body 10. Current is supplied to the lamp through a lead 12 connected to the socket contact 11. The body .10 is mounted within a tubular metal housing 13 and is biased outwards towards the lamp by a spring 14. The housing 13 is supported by a block 15 provided with cooling fins 16. The block is attached by screws to one end of a casing 17 forming the main structure of the fitting.

3,390,372 Patented June 25, 1968 ice FIG. 2 shows a clip formed in two halves 18 and 19 which are symmetrical about the line I-I, which indicates the plane of section of FIG. 1. The two halves of the clip have cooperating jaws 20 and 21 which engage on opposite sides of the seal 7 of the lamp. This seal has a generally I-shaped cross-section and the jaws 20 and 21 are shaped to accommodate it. A spring strip 22 embraces the two halves of the clip and holds the jaws in engagement with the seal. The halves of the clip have lugs 23 and 24 which can be pressed together to separate the jaws 20 and 21 against the force exerted by the spring 22 and thus enable the lamp to be removed.

As can be seen in FIG. 2, the jaws are at one end of the clip, the other end of which embraces the tubular housing 13. At this end the halves of the clip have the form of part-cylindrical shells, The clip is in good thermal contact with the housing 13 and heat from the region of the seal 7 in which the molybdenum strip 6 is embedded is conducted by the clip to the housing 13 and thence flows to the block 15 and is dissipated from the surface of this block and its fins 16. The clip also serves the purpose of supporting the lamp at the seal.

What we claim is:

1. A lamp fitting including a heat-conducting metal housing: a contact member mounted within the housing for engagement with a contact of the lamp; a metal clip attached around said housing and having jaws adapted to engage a part of the lamp envelope to be cooled, said clip being adapted to conduct heat from said lamp to the housing, said clip including a pair of cooperating jaws; means biasing said jaws toward each other, but adapted to be opened to separate said jaws from each other whereby said jaws will release their grip upon said lamp.

2. A fitting as claimed in claim 1 in which the housing is tubular.

3. A fitting as claimed in claim 1 in which the contact member is spring-loaded.

4. A fitting as claimed in claim 1 in which the clip consists of two parts, each carrying one of the jaws at one end and formed at the other end to engage over a part of the housing, and a spring element coupling the two parts together and biasing them towards the closed condition.

5. A fitting as claimed in claim 4 in which the housing is tubular, the said other end of each part of the clip is part cylindrical, and the spring element is a spring strip embracing the two parts.

6. A fitting as defined in claim 1 including cooling fins in thermal contact with the housing.

7. A lamp fitting as defined in claim 1 having mounted therein a tungsten-iodine lamp which has a molybdenum lead-in conductor sealed through the envelope of the lamp, with the jaws of the clip engaging the part of the lamp envelope through which the molybdenum conductor is sealed.

References Cited UNITED STATES PATENTS 2,662,220 12/1953 Saari 339-112 3,256,508 6/1966 Malm 339-144 940,021 11/1909 Howard et al 313-46 2,036,461 4/ 1936 Darby 339-255 X 2,172,086 9/1939 Marszalski 339-112 2,446,277 8/ 1948 Gordon 174-5063 3,097,903 7/1963 Moore 339-112 RICHARD E. MOORE, Primary Examiner.

ALFRED S. TRASK, EDWARD C. ALLEN, Assistant Examiners. 

1. A LAMP FITTING INCLUDING A HEAT-COMDUCTING METAL HOUSING: A CONTACT MEMBER MOUNTED WITHIN THE HOUSING FOR ENGAGEMENT WITH A CONTACT OF THE LAMP; A METAL CLIP ATTACHED AROUND SAID HOUSING AND HAVING JAWS ADAPTED TO ENGAGE A PART OF THE LAMP ENVELOPE TO BE COOLED, SAID CLIP BEING ADAPTED TO CONDUCT HEAT FROM SAID LAMP TO THE HOUSING, SAID CLIP INCLUDING A PAIR OF COOPERATING JAWS; MEANS BIASING SAID JAWS TOWARD EACH OTHER, BUT ADAPTED TO BE OPENED TO SEPARATE SAID JAWS FROM EACH OTHER WHEREBY SAID JAWS WILL RELEASE THEIR GRIP UPON SAID LAMP. 